5 research outputs found
Biotechnological Means for Genetic Improvement in Castor Bean as a Crop of the Future
Not AvailableProfitable cultivation of castor bean is beset
with problems of vulnerability of cultivars and
hybrids to a multitude of insect pests and
diseases. The presence of the toxic proteins
ricin and hyperallergenic Ricinus communis
agglutinin (RCA) in the endosperm restricts
the use of deoiled seed cake as cattle feed.
Due to this crop’s low genetic diversity,
genetic engineering can be an efficient
approach to introduce resistance to biotic
and abiotic stresses as well as seed quality
traits. Recently, castor oil gained attention as a
sustainable second-generation feedstock for
biojet fuel that would reduce carbon dioxide
emissions. Because of a growing interest in
castor oil as a biofuel and the presence of the
powerful toxin ricin in its seed, metabolic
pathways and regulatory genes involved in
both oil and ricin production have been
analyzed and characterized. Genetic engineering
of castor bean offers new possibilities to
increase oil yield and oxidative stability,
confers stress tolerance, and improves other
agronomics traits, such as reduced plant
height to facilitate mechanical harvesting.
However, difficulties in tissue culture-based
regeneration and poor reproducibility of results are major bottlenecks for genetic
transformation of castor bean. Despite
advances in tissue culture research over the
past four decades, direct or callus-mediated
adventitious shoot regeneration systems that
are genotype-independent remain a much
sought-after goal in castor bean. Genetic
transformation attempts to develop insect resistant
and ricin-free transgenic castor bean
lines have been based on shoot proliferation
from meristematic tissues. This chapter
describes new transformation methods under
development and the progress achieved so far
in genetic engineering of castor bean for
agronomically desirable attributes.Not Availabl
Not Available
Not AvailableCastor being a perennial, cross-pollinated, sexually polymorphic crop with high environmental sensitivity, initial plant breeding efforts were restricted to plant height and duration. Domestication of a wild, perennial crop to an annual crop of medium plant height and duration is the first success. Further, development of a two-line breeding system and standard seed production technology led to successful commercial exploitation of heterosis. Being a monotypic genus, diversification of parental base is restricted to intra-generic, intraspecific, or inter-varietal hybridization. Phenotypic expression is highly plastic and varies with locations and seasons. Majority of the morphological characters are monogenic, independently assorted with very limited linkages among the traits. However, information on genetics of major morphological characters is scattered in several old publications. Conventional breeding methods were successful in developing about 40 high-yielding hybrids and varieties with inbuilt resistance to major pests and diseases. An effort is made in the present chapter to consolidate the information on genetics and breeding methods followed in India and elsewhere.Not Availabl